The present invention pertains generally to automobiles having automatic transmissions, and particularly to a system for selectively controlling the actuation rate of the automatic transmission throttle valve.
The throttle valve, which is slidably movable in a bore, regulates the flow of transmission oil through the transmission""s valve body. A linkage couples the position of the accelerator pedal to the throttle valve, and causes the throttle valve to move between an idle or low throttle position and a full or wide open throttle position. Throttle valve controlled transmissions utilize a cable running from the vehicle""s fuel management system whether a fuel injector or carburetor to the transmission""s valve body. The cable linkage between a modem fuel injector/carburetor system provides a signal method for proper transmission function. The cable connection is commonly known as the throttle valve (TV) cable. The TV cable connects the throttle mechanism to the transmission hydraulic control valve. The throttle valve reciprocates in a common bore in the transmission valve body, and is typically composed of a plunger, spring, and throttle valve. The positioned relationship of these components determines how the transmission will operate.
The TV cable is used to connect the carburetor linkage at one end, to a swinging lever at the other end. The swinging lever moves the throttle valve. Any movements of the carburetor linkage, during normal driving, results in a corresponding movement of the TV cable. Carburetors have a range of movement from idle to wide open throttle. As normal carburetor linkage movement pulls the TV cable, the swinging lever rotates thereby pushing the throttle valve plunger down its bore. This plunger has a designed operating range from fully outwardly extended to fully inwardly depressed. Even slight movement of the throttle valve linkage results in a corresponding movement of the throttle valve. As the throttle valve moves, it will adjust the shift timing, feel, and firmness of the transmission.
For the throttle valve system to function properly, actuation of the throttle valve must be proper for the particular vehicle. Just because the plunger (and therefore the TV) is mechanically made to move through its engineered spectrum of movement, does not mean the transmission will perform in the desired manner. The rate of movement at any given point can be altered by the dynamics of the carburetor linkage, and can dramatically affect transmission performance characteristics. When new cars are designed, the correct linkage relationship is established for each particular vehicle. This is done to satisfy the different transmission operating responses needed for the different types of vehicles. For example, a luxury car""s TV system is not designed the same way as a performance car""s TV system, nor as a pickup truck""s TV system.
A problem exists when a throttle valve controlled transmission is to be installed in a vehicle for which it was not designed. Older automotive applications use carburetors for fuel management. All carburetors and modern fuel injection systems use a throttle shaft and a butterfly valve to control air intake. The available linkage attachment points on all popular carburetors and fuel injectors have both proven to be incorrect for proper TV control, and do not offer a method of xe2x80x9ctuningxe2x80x9d for different transmission responses. Of even more importance, older carburetor intake manifolds provide no correctly engineered point for mounting the TV cable. Additionally, the TV cable approach angle can have a dramatic effect on the dynamics of the cable pull.
Mechanisms for controlling transmission throttle valves are well known in the art. For example, U.S. Pat. No. 4,631,983 shows a lever mechanism for a cable linkage including a control lever mounted on a rotary shaft for rotation therewith, a base plate mounted on the rotary shaft and fixed to the control lever for rotation therewith, and a lever plate adjustably assembled with the base plate and connected at one side of its outer peripheral portion to one end of the cable linkage. The lever plate is provided at its outer peripheral portion with a semicircular guide surface having a center located substantially at a rotation fulcrum of the lever plate. The cable linkage is supported on the semicircular guide surface of the lever plate. And the lever plate is displaceable on the base plate. During the assembly process, the distance between the semicircular guide surface and the rotation fulcrum is adjustable.
U.S. Pat. No. 4,711,140 illustrates an improved throttle valve regulating system for automatic transmissions for motor vehicles. The throttle valve reciprocates in a bore as a result of the action of a plunger and a throttle valve spring to control the flow and pressure of transmission fluid or oil to effect gear shifting. A rigid spacing element of predetermined length received within the throttle valve spring is provided for urging the valve towards a full throttle position in the event that the valve sticks in the bore in a lower throttle position. The system further includes a high rate spring located in the full throttle position in the bore to prevent sticking of the valve in that position, and a low rate spring similarly positioned in the bore to counteract the force of the throttle valve spring for returning the throttle valve to a low throttle or zero position. The reciprocating throttle valve includes at least one land or circumferential flange having sharpened edges for shearing large particles or other impurities introduced into the bore with the transmission fluid which might otherwise become wedged between the valve and the bore and cause sticking of the valve in a fixed position in the bore.
U.S. Pat. No. 5,046,380 defines a throttle valve operating cam of an automatic transmission and an output control member of an automotive engine that are interconnected so as to cooperate with each other by a cable consisting of an outer tube and an inner cable. The inner cable is connected to the throttle valve operating cam and the output control member. One end of the outer tube is connected first to the automatic transmission. The other end of the outer tube is regulated in position relative to a cable fitting member secured to the automotive engine and then fixed to the cable fitting member secured to the automotive engine.
U.S. Pat. No. 5,295,408 discloses a strand end fitting having a housing adapted to be attached to a mounting pin located on a moveable member and having a passageway extending therethrough. The strand end fitting also includes a longitudinal member having an aperture therethrough telescopingly disposed within the passageway whereby a strand extends through the longitudinal member and has a retainer member secured thereon which abuts the longitudinal member. Once the longitudinal member is properly positioned within the housing, a locking structure prevents relative movement between the longitudinal member and the housing.
U.S. Pat. No. 5,727,425 comprises a method for adjusting the throttle valve cable in an automatic transmission. In a motor vehicle automatic transmission, for example a GENERAL MOTORS THM 700-R4 automatic transmission, the TV cable forms part of the mechanical link between the throttle pedal, the throttle valve linkage on a fuel delivery system (e.g., a carburetor or electronic fuel injector), and the throttle valve. The TV cable is adjusted using a sleeve and spring installed at the distal end of the TV cable between the cable end clamp and a teardrop shaped cable end fitting on the TV cable. The spring opposes the movement of the cable end fitting toward the distal end of the TV cable so that the cable end fitting is at its maximum distal position only at fully open throttle. This gives the vehicle operator the shift feel of a shorter TV cable at most throttle openings. The sleeve and spring are installed only on TV cables in automatic transmissions that do not have TV cable end fittings permanently attached to a throttle cam.
The present invention is directed to a system and method for controlling the throttle valve of automatic transmissions, and more particularly to a system and method which permits selective adjustment, or xe2x80x9ctuningxe2x80x9d, of the rate at which the throttle valve is activated to adjust shift timing, firmness, and feel. This allows the installation of a modern throttle valve controlled automatic transmission into a vehicle for which it was not designed. Specifically, the linkage on older carburetors was never designed to provide the proper signal to newer throttle valve transmissions. The present invention provides a means of insuring not only the correct cable pull distance, but also of adjusting the characteristics of transmission operation. The present invention offers an installer the ability to accomplish both a correct cable pull distance which is a requirement fixed by the travel of the throttle valve while concurrently offering many different dynamic arc or cable pull relationships to xe2x80x9ctunexe2x80x9d the transmission response to a desired shift timing, firmness, and feel. One way this is accomplished is by giving the installer the ability to maintain the TV cable""s approach angle in a fixed plane in relationship to the carburetor linkage. Through the use of spacers, a slot, and a hole pattern, the fixed plane may be raised or lowered to maintain a constant approach angle to the carburetor linkage attachment point. In a preferred embodiment, the approach angle is parallel to the bottom of the carburetor or fuel injection system. Another way the present invention allows the installer to tune the response is a sliding attachment point along a pre-engineered slot. The slot is designed to maintain a correct fixed pull distance at all slot positions while offering the installer wide latitude for adjusting the cable pull dynamics, including the rate at which the cable is pulled. As the attachment point is moved to different locations along the slot, the angular relationship between the pulling arm and the cable is changed. By using different settings along the slot, the transmission shift timing, firmness, and response aggressiveness can be adjusted over a wide spectrum. This provides the installer with a method of developing the desired transmission response while simultaneously maintaining the correct fixed cable pull distance.
In accordance with a preferred embodiment of the invention, an adapter plate is mounted beneath the fuel management device, a bracket is connected to the adapter plate, and the throttle valve cable is connected to the bracket.
In accordance with another preferred embodiment of the invention, the fuel management device has a rotatable linkage member to which is connected an adjustment mechanism having a slot. The throttle valve cable has a tubular housing fixedly connected to the bracket and a cable slidably disposed within the tubular housing. The first end of the cable is connected to the adjustments mechanism and an opposite second end is connected to the transmission throttle valve. The cable pull distance is substantially constant wherever the first end is selectively fixedly connectable along the slot.
In accordance with an important aspect of the invention, different first end connection positions along the slot result in correspondingly different rates of cable pull and therefore transmission response.
In accordance with an important feature of the invention, the slot can be either straight or slightly curved.
In accordance with another important aspect of the invention, the bracket is vertically adjustable with respect to the adapter plate.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.